Electromechanical brake applying device

ABSTRACT

The invention relates to an electromechanical brake applying device, especially for a rail vehicle brake, comprising a) an operating brake unit for producing a load-corrected and/or a skid-controlled brake force, b) an accumulation brake unit having an energy accumulator for storing and supplying energy for applying the brake, and c) an unlockable locking device for the energy accumulator. According to the invention, at least one control and monitoring device is provided for monitoring the brake function of the brake applying device. When the brake applying device is intact, a signal for keeping the locking device locked can be produced by said control and monitoring device, and in the event of safety braking and/or park braking, the operating brake unit can be activated in order to apply the brake.

STATE OF THE ART

The invention is based on an electromechanical brake application device,particularly for a rail vehicle brake, according to the preamble ofclaim 1.

Currently, three wheel braking systems are essentially used in the railvehicle field: Pneumatic or electro-pneumatic braking systems, hydraulicor electro-hydraulic braking systems as well as mechanical orelectromechanical braking systems. The wheel braking system may beconstructed as an active or passive braking system, depending on whetherthe power of the brake actuator has to be applied for the engaging(active braking system) or for the releasing of the brake (passivebraking system). In case of operating disturbances, energy is stored inair brake reservoirs if pneumatic systems are used; energy is stored inhydraulic reservoirs if hydraulic systems are used; and energy isaccumulated in the form of accumulator-type springs whenelectromechanical systems are used.

From the prior art, electromechanical brake application devices areknown which have a service-type brake unit as well as anaccumulator-type brake unit which has an energy accumulator. Theservice-type brake unit contains a braking power generator for theapplication and/or release of the brake; for example, in the form of anelectric-motor drive which can be controlled by a control device forslip-controlled or load-corrected braking. The accumulator-type brakeunit comprises at least one energy accumulator for the storage andsupply of energy for the application of the brake as a service-typeemergency brake during a safety braking demand; as a parking brake; orin the sense of an underlaid safety level, in the event of a failure ofthe service-type brake unit.

A power converter provides a conversion of the energy supplied by thebraking power generator and/or by the energy accumulator to a brakeapplication movement and comprises, for example, a brake spindle drivenby the electric-motor drive.

For activating the energy accumulator, a locking device is providedwhich can be unlocked upon a safety braking and/or parking brakingdemand signal. The accumulator-type brake unit is generally constructedas a spring brake, the accumulator-type spring being held in thetensioned condition by means of the locking device. Upon the safetybraking demand signal, which is controlled, for example, by way of asafety loop of the rail vehicle into the locking device, the latter isreleased and the power of the accumulator-type spring can be transmittedby means of the power converter to brake shoes.

However it is a disadvantage that, during a safety or parking braking,while the brake application device is intact, no non-skid-controlled orload-corrected feeding of the braking power can be achieved in order topermit a certain braking comfort also during safety and parking braking.

In view of the above, the present invention is based on furtherdeveloping an electromechanical brake application device of theinitially mentioned type such that, also during a safety braking and/orparking braking, a braking can take place in a non-skid-controlledand/or load-corrected manner.

According to the invention, this object is achieved by means of thecharacterizing features of claim 1.

ADVANTAGES OF THE INVENTION

When the safety braking or parking braking is demanded, while the brakeapplication device is intact, a braking can take place in completecomfort, that is, in a load-corrected and or slip—or non-skid-controlledmanner, by means of the service-type brake unit. The controlling-in ofthe braking power is monitored in this case by the control andmonitoring device. When the controlling-in of the braking power iscorrect (brake application device is intact), this control andmonitoring device prevents the opening of the locking device and thus,in the event of a safety braking, the brake slip of the wheels of therail vehicles which is frequently observed when the accumulator-typebrake unit is triggered. As a result of this measure, the drivingcomfort can be increased and the mechanical loads and the wear of thebrake system can be reduced.

As a result of the measures indicated in the subclaims, advantageousfurther developments and improvements of the electromechanical brakeapplication device indicated in claim 1 can be achieved.

According to a particularly preferable measure, in the case of an intactbrake application device, a feeding of the safety braking and/or parkingbraking signal to the locking device can be prevented by means of aswitching device, which can be controlled by the control and monitoringdevice, and instead a signal for maintaining the locked condition can becontrolled in.

The locking device preferably has an electromagnetically operableconstruction, can be locked when energized and can be unlocked when notenergized, the safety braking demand signal being formed by acurrentless condition which can be controlled in by way of a safety loopof the rail vehicle.

The switching device contains at least one relay which, upon the safetybraking demand signal and when the brake application device is intact,connects the locking device with a voltage source. An unlocking of theaccumulator-type brake unit will then be reliably prevented by means ofsimple devices.

As an alternative, the locking device may have several locking elements,of which at least one locking element is sufficient for keeping thelocking device locked, in which case, when the brake application deviceis intact, the control and monitoring device can output to this at leastone locking element the signal for keeping the locking device locked.

The latter can be implemented, for example, in that the locking deviceis electromagnetically operable and contains several solenoid coils asthe locking elements for generating magnetic forces which lock or unlockthe locking device, the magnetic force of at least one solenoid coilcontrollable by the control and monitoring device being sufficient forkeeping the locking device locked. When the locking device isconstructed with a double or multiple coil, a separate control of theindividual coils can be implemented in mutually separated electriccircuits, for example, by means of the control and monitoring device, onthe one hand, and by means of a safety loop of the rail vehicle, on theother hand. Solenoid coils are identical parts; one or two additionalsolenoid coil(s) take up only a little more space. For this reason, thedescribed solution requires little space and can be implemented in acost-effective manner. Furthermore, solenoid coils are unsusceptiblewith respect to shock loads or vibration loads and have a long servicelife.

DRAWINGS

Embodiments of the invention are illustrated in the drawings and areexplained in detail in the following description.

FIG. 1 is a very schematic representation of a preferred embodiment of abrake application device according to the invention;

FIG. 2 is a sectional view of a locking device according to anotherembodiment of the brake application device.

DESCRIPTION OF THE EMBODIMENTS

The preferred embodiment of an electromechanical brake applicationdevice of a rail vehicle marked by reference number 1 in FIG. 1 containsa service-type brake unit with a brake actuator 2 which comprises abrake spindle 6 which can be driven by and electric servo motor 4. Thebrake spindle 6 is surrounded by a nut/spindle constructional unit 8which preferably can be constructed as a roller thread drive, such as acirculating ball spindle, a roller thread drive, a thread roller screwdrive or as a planetary roller thread drive. Therefore, during rotationsof the brake spindle 6, a nut 10 of the nut/spindle constructional unit8 is translatorily guided along the brake spindle 6 and, in the process,acts upon swivellably linked caliper levers 12. The swivelling movementsof the caliper levers 12 are converted to essentially translatory brakeapplication movements of brake linings in the direction of a brake diskaxis which is not shown.

The service-type brake unit is constructed for generating load-correctedand/or slip-controlled braking powers, a load-corrected braking powerbeing a braking power which is essentially adapted to the respectivelypresent weight of the rail vehicle, and a slip-controlled braking poweris a braking power by means of which the braking takes place with nowheel slip or only a little wheel slip. For this purpose, a controldevice 16 is provided into which, by means of a signal line 18, a signalfor the actual braking power value can be controlled by a first powersensor 20 and can be compared there with a desired braking power valuefor determining a control difference. The desired braking power valuedefinition is preferably oriented according to the reaching of ademanded braking power in a time period that is as short as possible.

The control device 16 controls a power part 22 which, as a function ofthe computer control difference outputs an operating current for theservo motor 4, which is measured by a current sensor 24, a correspondingsignal being transmitted by way of a signal line 26 to the controldevice 16. The build-up of the braking power starts only after a liningplay has taken place. A rotational speed sensor 28 is used as a positionsensor or as a angle-of-rotation generator for a correct control of themotor by the control device 16.

Furthermore, the brake application device 1 contains an accumulator-typebrake unit with an energy accumulator for storing and supplying energyfor the application of the brake in the event of a safety braking or anemergency braking. The energy accumulator is preferably formed by anaccumulator-type spring 30 which is constructed as a coil spring, iscoaxial with respect to the brake spindle, is tensioned in the brakerelease position and is supported by means of its end facing the servomotor 4 on a housing of the brake actuator 2 and, by means of its otherend, on a sliding sleeve, which is not shown for reasons of scale, canbe displaced coaxially with respect to the brake spindle 6, acts uponthe caliper levers 12 and can be held in the release position by meansof a locking device 32.

By way of an electric line 34, the locking device 32 is connected with asafety loop 36 of the rail vehicle, on which a safety braking demandsignal is present as a result of the operating of an emergency strikingbutton or an emergency brake lever. A switching device 38 is arrangedbetween the safety loop 36 and the locking device 32, which switchingdevice 38 preferably comprises two series-connected relays—a first relay40 and a second relay 42. As an alternative, any other type of switchingelement can be used, such as semiconductors, particularly transistors.

By means of its control input 44, the first relay 40 is connected by wayof an electric control line 46 with a control and monitoring device 48integrated in the control device 16; the control input 50 of the secondrelay 42 is connected by means of another control line 52 to anotherredundant control and monitoring device 54 which can communicate withthe one control and monitoring device 48. Both relays 40, 42 areconnected with their respective power inputs 56, 58 with a voltagesource 60; another power input 62 of the second relay 42 is connectedwith the safety loop 36, and its output 64 is connected with theadditional power input 66 of the first relay 40, an output 68 of thefirst relay 40 being connected by way of the electric line 34 with thelocking device 32. When they are not energized, both relays 40, 42conduct the electric line 34 between the locking device 32 and thesafety loop 36, as illustrated in FIG. 1. The two control and monitoringdevices 48, 54 can receive signals of the safety loop 36 by way ofelectric lines 70. By way of an interface 72, braking demand signals ofa brake signal generator arrive at the control device 16. In addition, asystem diagnosis can take place by way of the interface; furthermore,the interface represents a connection to a higher-ranking control.

A second power sensor 74 is connected by way of a signal line 76 withthe redundant control and monitoring device 54. The output signals ofthe two power sensors 20, 74, as input signals for the control andmonitoring devices 48, 54 and the control device 16, in addition toforming actual braking power values required for the computing of thecontrol difference, also form criteria for the operability of the brakeapplication device 1. The function test of the brake application device1 preferably takes place online and continuously by means of the twocontrol and monitoring devices 48, 54. Instead of directly measuring thebraking power, sensors may also be provided for measuring physicalquantities, from which the braking power can be derived.

The locking device 32 preferably has an electromagnetically operableconstruction and comprises a locking piston 78 which, when the lockingdevice 32 is energized, locks the accumulator-type spring 30 in itstensioned position and, when the locking device 32 is not energized,unlocks the accumulator-type spring 30, so that the relaxingaccumulator-type spring 30 can cause a brake application movement of thebrake linings 14.

The servo motor 4 forms a braking power generator; the other elements ofthe power transmission path from the servo motor 4 to the brake linings14 form a braking power converter. Before this background, the brakeapplication device 1 according to the preferred embodiment has thefollowing function:

In the release position of the brake actuator 2, the accumulator-typespring 30 is tensioned. The two relays 40, 42 are in the switchingposition illustrated in FIG. 1, in which the locking device 32 iselectrically connected with the safety loop 36. Since the safety loop 36is energized in the normal operation, the locking device 32 is in thelocked position. The force of the tensioned accumulator-type spring 30can then be suppressed by the locking device 32.

During the transition from the release position to the service-typebraking position, the control device 16 receives a braking demand signalby way of its interface 72, whereupon the servo motor 4 is driven by wayof the power part 22 and the brake spindle 6 is caused to rotate,whereby the nut 10 of the nut/spindle constructional unit 8 is screwedalong the brake spindle 6 and the caliper levers 12 are spread. Theaccumulator-type spring 30 does not participate in the generating of theservice-type braking power and remains in the tensioned conditionbecause it is locked by the still energized locking device 32.

When an emergency striking button or an emergency brake lever of therail vehicle is operated, a safety braking demand signal is generated inthe safety loop 36, which safety braking demand signal is preferablygenerated by switching the safety loop 36 currentless. If it wasdetermined by one or both control and monitoring devices 48, 54 that thebrake application device 1 is without any defect, for example, by meansof the braking power time courses of preceding brakings, the two relays40, 42 are switched over such that the locking device 32 is energized bythe voltage source 60. As a result, the locking device 32 remains lockeddespite the presence of the safety braking demand signal on the safetyloop 36, and the accumulator-type spring 30 cannot relax. The safetybraking demand signal generated by switching the safety loop 36currentless, is therefore overwritten by the current supply of thelocking device 32 generated by means of the control and monitoringdevices 48, 54. Simultaneously, a service braking is triggered by thetwo control and monitoring devices 48, 54 switched currentless by way ofthe safety loop 36 on the control input side, during which servicebraking, by means of the servo motor 4, a slip-controlled and/or loadcorrected braking power is generated on the brake linings 14. If one ofthe two control and monitoring devices 48, 54 fails, its function can ineach case be taken over by the other. In particular, the two relays 40,42 are also switched such that, if one relay 40, 42 fails, therespective other relay 40, 42 can still provide an electric connectionbetween the locking device 32 and the voltage source 60.

However, if one or both control and monitoring devices 48, 54 detect adefect in the brake application device 1, the two relays 40, 42 receiveno switch-over signals from the control and monitoring devices 48, 54and remain in their conduction position illustrated in FIG. 1. Becauseof the safety loop 36 switched currentless by the operation of theemergency striking button, the locking device 32 also receives no morecurrent so that it unlocks the accumulator-type spring 30. The brakingby means of the accumulator-type brake unit will then take place withoutslip control and without load correction.

FIG. 2 shows a locking device 80 according to another embodiment of thebrake application device 1 according to the invention. The remainingcomponents of the brake application device 1 are identical or analogouswith the components described above. The following explanations relateto the construction of the locking device 80.

In an actuator housing 82 of the brake actuator 2, an annulus 84 isconstructed in which a ring gear 90 is arranged which is in a drivingconnection with a locking nut 86 by means of a slipping clutch 88. Thelocking nut 86 can be rotated by means of a non-self-locking thread 92with respect to a sliding sleeve 94 which is displaceable in thedirection of the brake spindle and on which the accumulator-type spring30 is supported and whose translatory moving-out movement causes aswivelling of the caliper lever 12 in the brake application direction.The locking device 80 has a housing 96 which is flanged to a radialopening of the annulus 84. In addition, the locking device 80 comprisesa shaft 98, on whose radial interior end, a bevel gear 100 is arrangedand, on whose opposite radially exterior end, a cylindrical inertia disk102 is arranged. The bevel gear 100 meshes with the toothing of the ringgear 90 and, together with it, forms a bevel gear pair which preferablyhas a relatively high transmission ratio. The shaft 98 is rotatablydisposed in the housing 96 of the locking device 80 by means of deepgroove ball bearings 104, the shaft 98 being arranged perpendicular withrespect to the brake spindle 6.

On its face pointing to the brake spindle 6, the inertia disk 102 has aring recess 106 for a ring 108 which is arranged coaxial to the shaft 98and is displaceably received along pins 110 extending in the axialdirection, whereby it is non-rotatably connected with the inertia disk102. In addition, the ring 108 has a radially external gear rim 112 onits face pointing away from the inertia disk 102, which gear rim 112 issituated opposite another gear rim 114 supported on the housing 96 ofthe locking device 80 and is pushed away from that gear rim 114 as aresult of the effect of pressure springs 116. Furthermore, several,preferably two solenoid coils 118, 120 arranged behind one another inthe axial direction in the housing 96 of the locking device 80 aresituated opposite the ring 108, which solenoid coils 118, 120 can beindividually energized by electric connections 122. Together, the ring108, the two gear rims 112, 114 and the two solenoid coils 118, 120 forma solenoid cogwheel brake 124.

In the case of at least one energized solenoid coil 118, 120, magneticattraction powers are generated which move the ring 108 against theeffect of the pressure springs 116 along the pins 110 in the axialdirection toward the solenoid coils 118, 120, whereby the gear rim 112of the ring 108 comes to engage with the gear rim 114 held on thehousing 96 of the locking device 80 and thus enters into a non-rotatableconnection therewith. Then, a torque acting from the accumulator-typespring 30 upon the sliding sleeve 94 and introduced by way of thelocking nut 86 and the ring gear 90 into the locking device 80 can besupported on the housing 96 of the locking device 80, the flux of forceextending through the bevel gear 100, the shaft 98 and the inertia disk102. The solenoid coils 118, 120 act magnetically in the same directionand are designed such that the magnetic force of a single solenoid coil118, 120 is sufficient for keeping the solenoid cogwheel brake 124closed.

The solenoid coil 120, which is situated farther away from the ring 108,is in an electrically conductive connection by way of the connections122 with the control and monitoring devices 48, 54 illustrated in FIG. 1and receives current from this connection, while the solenoid coil 118situated closer to the ring 108 is connected to the safety loop 36. Asan alternative, a reverse assignment is conceivable. This means that, ifthe safety loop 36 is switched currentless, the solenoid coil 118receives no current during a safety braking and therefore also generatesno magnetic forces for locking the solenoid cogwheel brake 124. However,in the case of an intact brake application device, the safety brakedemand signal generated during the switching to the currentlesscondition is overwritten in that the other solenoid coil 120 continuesto be energized by the control and monitoring devices 48, 54, in whichcase the resulting magnetic forces are sufficient for keeping thesolenoid cogwheel brake 124 and thus the locking device 80 locked, sothat the accumulator-type spring 30 cannot relax. In this case, as inthe case of a service-type braking, the safety braking power will thenbe generated by the servo motor 4 controlled by the control device 16.

In addition or as an alternative, while the brake application device 1is intact, at least one of the solenoid coils of the solenoid cogwheelbrake 124 is energized by the control and monitoring devices 48, 54 or,as a result of the latter, remains in the energized condition if anothersolenoid coil is switched currentless because of the presence of aparking brake demand signal. Also in this case, the parking brake power,as in the case of a service braking, is generated by the servo motor 4controlled by means of the control device 16.

In order to achieved a reduction of the power loss, the solenoid coil120 controlled by the control and monitoring devices 48, 54 is operatedby means of a holding current which is just high enough for holding thesolenoid cogwheel brake 124 closed. As a result, the current consumptionas well as the internal heating of the brake application device 1 isreduced.

If, however, the brake application device 1 should have a defect, thesolenoid coil 120 is also switched currentless so that the gear rim 112of the ring 108, as a result of the pressure springs 116, disengagesfrom the gear rim 114 held at the housing 96 of the locking device 80and, for this reason, the ring gear 90, together with the bevel gear100, the shaft 98 and the inertia disk 102 can rotate freely withrespect to the housing 96 of the locking device 80. As a result, thelocking nut 86 can rotate along the non-self-locking thread 92 on thesliding sleeve 94 which is forced into the brake application position bythe accumulator-type spring 30. As in the case of the above-describedembodiment, the safety braking triggered by the accumulator-type spring30 takes place without any slip control and without any load correction.

The inertia disk 102, the ring 108, the shaft 98 and the bevel gear 100,together, form an inertia weight 126 which can be rotated perpendicularto the brake spindle 6 and, relative to the slipping clutch 88, isarranged on the other side of the locking nut 86, because of its radius,the inertia disk 102 fraction of the mass moment of inertia of theinertia weight 126 being the largest. During the brake applicationmovement, the rotation of the locking nut 86 is translated by way of thebevel gear pair 90, 100 into a rotation of the inertia weight 126 whichtakes place at a higher rotational speed, so that a large portion of thepotential energy of the relaxing accumulator-type spring 30 is convertedto rotational energy.

When the braking position has been reached, the rotation of the lockingnut 86 will stop. The slipping clutch 88 between the locking nut 86 andthe ring gear 90 is designed such that the upper limit torque, startingat which a relative rotation can take place between the radialserrations 128 of the ring gear 90 and of the locking nut 86, isexceeded by the torque from the product of the mass moment of inertia ofthe inertia weight 126 and of the deceleration in the braking endposition existing after passing through the brake application stroke, sothat, after the braking end position has been reached, the inertiaweight 126 can first continue to rotate and, essentially as a result ofthe friction taking place between the radial serrations 128 of the ringgear 90 and of the locking nut 86, is slowly caused to come to a stop.As a result, a gradual reduction of the rotational energy accumulated inthe inertia weight 126 can take place.

For engaging the parking brake by means of the accumulator-type brakeunit, all solenoid coils 118, 120 can be switched currentless bysuitable measures in order to release the locking device 80. As analternative and as a result of the reversal of the current flow in oneor in both solenoid coils 118, 120, the direction of the magnetic forcescan be inverted and thus the solenoid cogwheel brake 124 can be opened.Furthermore, another solenoid coil can be used which can be energizeddirectly by way of a control line assigned to the parking brake andgenerates magnetic forces which counteract the magnetic forces of thetwo solenoid coils 118, 120.

List of Reference Numbers

-   1 Brake application device-   2 brake actuator-   4 servo motor-   6 brake spindle-   8 nut/spindle constructional unit-   10 nut-   12 caliper lever-   14 brake linings-   16 control device-   18 signal line-   20 power sensor-   22 power part-   24 current sensor-   26 signal line-   28 rotational speed sensor-   30 accumulator-type spring-   32 locking device-   34 electric line-   36 safety loop-   38 switching device-   40 relay-   42 relay-   44 control input-   46 control line-   48 control and monitoring device-   50 control input-   52 control line-   54 redundant control and monitoring device-   56 power input-   58 power input-   60 voltage source-   62 power input-   64 output-   66 power input-   68 output-   70 electric line-   72 interface-   74 power sensor-   76 signal line-   78 locking piston-   80 locking device-   82 actuator housing-   84 annulus-   86 locking nut-   88 slipping clutch-   90 ring gear-   92 non-self-locking thread-   94 sliding sleeve-   96 housing locking device-   98 shaft-   100 bevel gear-   102 inertia disk-   104 deep groove ball bearing-   106 ring recess-   108 ring-   110 pin-   112 gear rim-   114 gear rim-   116 pressure springs-   118 solenoid coil-   120 solenoid coil-   122 electric connection-   124 solenoid cogwheel brake-   126 inertial weight-   128 radial serrations

1. An electromechanical brake application device for a rail vehiclebrake, the device comprising: a) a service-type brake unit forgenerating a load-corrected and/or slip-controlled braking power; b) anaccumulator-type brake unit having an energy accumulator for storing andsupplying energy for the application of the brake, c) an unlockablelocking device for the energy accumulator; and d) at least one controland monitoring device monitoring the braking function of the brakeapplication device; the control and monitoring device, when the brakeapplication device is intact, generates a signal for keeping the lockingdevice locked and, also in the event of a safety and/or parking braking,the service-type braking unit is activated for applying the brake. 2.The electromechanical brake application device according to claim 1,wherein, when the brake application device is intact, the control andmonitoring device constantly generates signals for keeping the lockingdevice locked and overrides a safety and/or parking braking demandsignal it generated for the unlocking of the locking device.
 3. Theelectromechanical brake application device according to claim 1,wherein, when the brake application device is intact, the control andmonitoring device prevents supplying of a safety and/or parking brakingdemand signal to the locking device by means of a switching device andinstead controls the signal for keeping the locking device locked. 4.The electromechanical brake application device according to claim 3,wherein the locking device has an electromagnetically operableconstruction, can be locked in an energized condition and can beunlocked when it is not energized, the safety braking demand signalbeing formed by a currentless condition which can be controlled by asafety loop of the rail vehicle.
 5. The electromechanical brakeapplication device according to claim, wherein the switching devicecontains at least one relay which, upon the safety braking demand signaland when the brake application device is intact, connects the lockingdevice with a voltage source.
 6. The electromechanical brake applicationdevice according to claim 1, wherein the locking device contains severallocking elements, of which at least one locking element is sufficientfor keeping the locking device locked, the signal for keeping thelocking device locked being controllable from the control and monitoringdevice to this at least one locking element when the brake applicationdevice is intact.
 7. The electromechanical brake application deviceaccording to claim 6, wherein the locking device is electromagneticallyoperable and, as the locking elements, contains several solenoid coilsfor generating magnetic forces locking or unlocking the locking device,the magnetic force of at least one solenoid coil controllable by thecontrol and monitoring device being sufficient for keeping the lockingdevice locked.
 8. The electromechanical brake application deviceaccording to claim 1, wherein the control and monitoring device isintegrated in a control device for the slip control and/or the loadcorrection of the braking power generated by the service-type brakeunit.
 9. The electromechanical brake application device according toclaim 8, wherein the braking power is constantly monitored with respectto the amount and the duration of action by the control and monitoringdevice.
 10. The electromechanical brake application device according toclaim 9, wherein the control and monitoring device is connected with asensor for measuring physical quantities, from which the braking powergenerated by the service-type brake unit can be derived.
 11. Theelectromechanical brake application device according to claim 10,wherein the output signal of the at least one sensor with the inputsignal for the control and monitoring device forms a criterion for theoperability of the brake application device.
 12. The electromechanicalbrake application device according to claim 11, including an additionalredundant control and monitoring device controlling the locking device.13. The electromechanical brake application device according to claim 1,wherein the locking device has an electromagnetically operableconstruction, can be locked in an energized condition and can beunlocked when it is not energized, the safety braking demand signalbeing formed by a currentless condition which can be controlled by asafety loop of the rail vehicle.
 14. The electromechanical brakeapplication device according to claim 3, wherein the switching devicecontains at least one relay which, upon the safety braking demand signaland when the brake application device is intact, connects the lockingdevice with a voltage source.